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| United States Patent |
5,229,808
|
|
VanDeMoere
, et al.
|
July 20, 1993
|
Camera viewfinder
Abstract
In a photographic camera, a neutral density or other light reducing filter
in the viewfinder obscures details of a subject viewed through the
viewfinder in low light to provide a warning that ambient light is
insufficient for a proper daylight exposure. The filter has little or no
light reducing capability at a central portion and along a peripheral
portion to serve as aiming and framing features, respectively.
| Inventors:
|
VanDeMoere; Alan V. (Rochester, NY);
Hodder; David A. (Spencerport, NY)
|
| Assignee:
|
Eastman Kodak Company (Rochester, NY)
|
| Appl. No.:
|
823940 |
| Filed:
|
January 22, 1992 |
| Current U.S. Class: |
396/295; 396/373 |
| Intern'l Class: |
G03B 007/00 |
| Field of Search: |
354/411,219-225
356/234,235
|
References Cited
U.S. Patent Documents
| 1255167 | Feb., 1918 | Howie | 354/411.
|
| 1420096 | Jun., 1922 | Hague | 354/411.
|
| 1614672 | Jan., 1927 | Herz | 354/411.
|
| 1721411 | Jul., 1929 | Ramsey | 354/411.
|
| 2066605 | Jan., 1937 | Billing | 354/411.
|
| 2219300 | Oct., 1940 | Edmunds | 354/411.
|
| 2273429 | Feb., 1942 | Bing | 354/411.
|
| 2321420 | Jun., 1943 | Rath | 354/411.
|
| 2350237 | May., 1944 | Kende et al. | 354/411.
|
| 3429243 | Feb., 1969 | Boyle, Jr. | 354/411.
|
| 3760700 | Sep., 1973 | Trankner et al. | 354/411.
|
| 4474441 | Oct., 1984 | Millard | 354/413.
|
Primary Examiner: Gellner; Michael L.
Assistant Examiner: Blankenship; Howard B.
Attorney, Agent or Firm: Fields; Roger A.
Claims
We claim:
1. A camera viewfinder through which a subject to be photographed is
viewed, comprising a light-reducing filter arranged across a viewing axis
of said viewfinder for making the subject appear faint when it is viewed
through the viewfinder in ambient light that is insufficient for a proper
daylight exposure, is characterized in that:
said filter has a central portion substantially at the viewing axis of said
viewfinder with little or no light reducing capability as compared to a
surrounding portion of the filter to permit the subject to be viewed
through said central portion can more readily than it can be viewed
through said surrounding portion, whereby the central portion can be used
to aim at the subject.
2. A camera viewfinder as recited in claim 1, characterized further in
that:
said filter has a peripheral portion with little or no light reducing
capability as compared to said surrounding portion of the filter to permit
the subject to be viewed through said peripheral portion more readily than
it can be viewed through the surrounding portion, whereby the peripheral
portion can be used to frame the subject.
3. A photographic camera recited in claim 1, wherein said filter is a
neutral density filter.
4. A photographic camera as recited in claim 1, wherein said central
portion of said filter includes a viewing hole for aiming at the subject.
5. A photographic camera as recited in claim 1, wherein said central
portion of said filter is less thick than said surrounding portion of the
filter for aiming at the subject.
6. A camera view finder through which a subject to be photographed is
viewed, comprising a light-reducing filter arranged across a viewing axis
of said viewfinder for making the subject appear faint when it is viewed
through the viewfinder in ambient light that is insufficient for a proper
daylight exposure, is characterized in that:
said filter has an encircling peripheral portion with little or no light
reducing capability as compared to a main portion of the filter to permit
the subject to be viewed through said peripheral portion more readily than
it can be viewed through the main portion, whereby the peripheral portion
can be used to frame the subject.
7. A photographic camera as recited in claim 6, wherein said peripheral
portion of said filter is less thick than said main portion of the filter
for framing the subject.
Description
CROSS-REFERENCE TO A RELATED APPLICATION
Reference is made to commonly assigned copending application Ser. No.
07/823,951 entitled CAMERA VIEWFINDER and filed Jan. 22, 1992 in the name
of Alan V. VanDeMoere.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to the field of photography, and in
particular to a camera viewfinder. More specifically, the invention
relates to a camera viewfinder in which a neutral density or other light
reducing filter obscures details of a subject viewed through the
viewfinder in low light to provide a warning that ambient light is
insufficient for a proper daylight exposure.
2. Description of the Prior Art
When taking a picture it is necessary to know not only in what direction to
aim the camera but also how much of the subject will be included in the
picture. For this reason practically every camera has a viewfinder of some
kind.
Typical prior art U.S. Pat. No. 1,255,167, issued Feb. 5, 1918, discloses a
viewfinder with a disk that is rotatable to bring respective openings in
the disk successively into registration with a front lens of the
viewfinder. Some of the openings are covered by different color light
retarding materials to change the amount of ambient light that can enter
the viewfinder through the front lens, and they have corresponding
notations indicating recommended times of exposure. In operation, the disk
is manually rotated until the opening in registration with the front lens
makes the subject viewed through the viewfinder appear somewhat faint.
Then, the associated time of exposure is selected. If, however, the
subject is too faint, the associated time of exposure is too short. A
problem with the design is that it may be difficult to aim the camera at
the subject and to frame the subject because the view of the subject
through the viewfinder is made faint.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a camera
viewfinder for viewing a subject to be photographed, which comprises
light-reducing filter means arranged across a viewing axis of the
viewfinder for making the subject appear faint when it is viewed through
the viewfinder in ambient light that is insufficient for a proper daylight
exposure, and which is characterized in that:
said filter means has a central portion substantially at the viewing axis
of the viewfinder with little or no light reducing capability as compared
to a main or surrounding portion of the filter means to permit the subject
to be viewed through the central portion more readily than it can be
viewed through the main portion, whereby the central portion can be used
to aim at the subject.
According to another aspect of the invention the camera viewfinder is
characterized further in that:
said filter means has a peripheral portion with little or no light reducing
capability as compared to the main portion of the filter means to permit
the subject to be viewed through the peripheral portion more readily than
it can be viewed through the main portion, whereby the peripheral portion
can be used to frame the subject.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front perspective view of a photographic camera including a
viewfinder construction according to a preferred embodiment of the
invention;
FIG. 2 is a front perspective view of an integral front wall and taking
lens extension of the camera housing;
FIG. 3 is a top view of the photographic camera with part of its top cover
removed to show the viewfinder construction;
FIG. 4 is a cross-section view of a neutral density filter included in the
viewfinder construction; and
FIG. 5 is a front elevation view of the neutral density filter.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The invention is disclosed in connection with a 35 mm camera. Because such
a camera is widely known, this description is directed in particular to
photographic elements forming part of or cooperating directly with the
invention. It is to be understood, however, that other elements not
specifically shown or described may take various forms known to persons of
ordinary skill in the art.
Referring now to FIGS. 1 and 3 of the drawings there is shown a
photographic camera 1 comprising a camera housing or body 3 which has an
internal viewfinder tunnel 5 bounded by a viewing opening 7 in a rear wall
9 of the housing and a frame finder opening 11 in a front wall 13 of the
housing. A taking lens extension or snout 15 projects longitudinally from
the front wall 13 and has a front end or panel 17 that supports a lens
element 19. Typically, when aiming the photographic camera 1 at a subject
to be photographed, one places an eye at the viewing opening 7, looks
through the internal viewfinder tunnel 5, and out the frame finder opening
11.
The taking lens extension 15 has a channel-like cut-out 21 substantially
along its length which converges toward the frame finder opening 11 to
effectively extend the viewfinder tunnel 5 to facilitate camera aiming.
See FIGS. 1 and 3. The channel-like cut-out 21 is defined by a pair of
upstanding spaced walls 23 and 25 of the taking lens extension 15 which
converge from the front end 17 of the taking lens extension rearwardly to
respective sides 27 and 29 of the frame finder opening 11. See FIG. 2.
Also, the channel-like cut-out 21 is defined by a floor 31 which extends
between the spaced walls 23 and 25 from the front end 17 of the taking
lens extension rearwardly to a bottom 33 of the frame finder opening 11.
The bottom 33 of the frame finder opening 11 lies between the two sides 27
and 29 of the frame finder opening. See FIG. 2. Other details of the
channel-like cut-out 21 are provided in cross-referenced application Ser.
No. 07/823,951.
A light reducing semi-transparent filter, such as a neutral density filter
35, is fixed across the frame finder opening 11 to make the subject to be
photographed appear faint or obscured when the camera user views it
through the viewfinder tunnel 5 in ambient light that is insufficient for
a proper daylight exposure. See FIGS. 1 and 3. Specifically, if the camera
user can see details of the subject, there is enough light to take an
acceptable picture. Conversely, if the camera user cannot see details of
the subject, the light level is too low to take a good picture. In one
example, there was selected a film speed of ISO 1600, an 85 mm taking
lens, an exposure aperture of f/11, and an exposure time of 1/125 second.
Given an underexposure latitude of two f/stops, unacceptable pictures are
expected to occur at ambient light of 12 or lower foot-lamberts.
Subjective testing then led to a neutral density filter 35 with a 1.6 to
1.8 log density.
According to a first aspect of the invention, the neutral density filter 35
has a central portion 37 substantially at a viewing axis X of the
viewfinder tunnel 5 with little or no light reducing capability as
compared to a main or surrounding portion 39 of the filter. See FIGS. 4
and 5. This permits the subject to be viewed through the central portion
37 more readily than it can be viewed through the main or surrounding
portion 39. As a result, the central portion 37 can be used as a pointing
or aiming device to aim at the subject when looking through the viewfinder
tunnel 5. Preferably, the central portion 37 is a round viewing hole 41 in
the filter 35. Alternatively, the central portion 37 can be less thick or
less dense than the main or surrounding portion 39. What is necessary to
make a pointing or aiming device is that a central "bright spot" be
apparent in the viewfinder tunnel 5 when looking at the subject. Also, it
has been determined that the central "bright spot" can serve as a good
base or reference standard for the camera user to judge if the subject
appears faint when viewed through the main or surrounding portion 39. In
place of the round viewing hole 41, other shapes may be employed as the
aiming device. These include crosshair designs, rectangular-line designs,
etc.
According to another aspect of the invention, the neutral density filter 35
has an encircling peripheral portion 43 with little (or no) light reducing
capability, i.e. less thick or less dense, as compared to the main or
surrounding portion 39 of the filter. See FIGS. 4 and 5. This permits the
subject to be viewed through the peripheral portion 43 more readily than
it can be viewed through the main or surrounding portion 39. Consequently,
the peripheral portion 43 can be used to frame the subject.
The invention has been described with reference to a preferred embodiment.
However, it will be appreciated that variations and modifications can be
effected within the ordinary skill in the art without departing from the
scope of the invention.
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